Apparatus for treating cement raw material and the like



March 16, 1943. c, WANNER I 2,314,296

APPARATUS FOR TREAIING CEMENT RAW MATERIAL AND THE LIKE 1 Filed April25, 1941 Patented Mar. 1 6, 1943 UNITED STATES PATENT OFFICE APPARATUSFOR TREATING CEMENT RAW treatment of cement and similar materials and toprocesses for effecting such treatment, and is directed particularly toimprovements in apparatus and processes for the burning of Portlandcement and other hydraulic cements and limestones.

The prior U. S. Patents to Otto Lellep, Nos. 1,775,313, 1,992,704, and1,994,7l8, disclose a process and apparatus for the treatment of cementraw material which is highly efllcient. The basic feature of the Lellepprocess, which involves the treatment of cement and similar materialsprior to the sintering thereof in a rotary kiln, is the use of the wastekiln gases to effect preliminary or partial calcining of the material.Thus in the preferred form of the Lellep apparatus, cement material isdelivered to a traveling grate or gas pervious conveyor and is moved insuccession through two zones. In the first of these zones the material,in the form of slightly moist nodules or agglomerates of fairly uniformsize, is dried at a moderately high temperature, and thereafter passesinto the second or precalcining zone, in which the temperature issubstantially higher. The waste kiln gases act directly on the" materialin each of these zones, being drawn downwardly through the bed ofmaterial and through the supporting grate, and the difference intemperature in the two zones is obtained by providing for the directpassage of the exhaust gas from the kiln into the precalcining zone andfor indirect passage of the gas from the precalcining to the predryingzone. Thus it is possible to prevent explosion and disruption of theagglomerates or nodules by drying the latter relatively slowly beforethey are subjected to the action of the highly heated gases issuingdirectly from the kiln.

In the Lellep patents it is contemplated that the cement raw materialsubjected to the process shall be supplied in pulverulent and generallydry form, and agglomerated by spraying with water in a suitableagglomerating drum, such as is'jdescribed in the patents. Theeffectiveness of the process can be very largely attributed 'to the factthat the material is presented to the action of the kiln exhaust gasesin the form of nodules of reasonably uniform size through which thegases may readily be passed. Reduction of size or breaking up of thenodules would impede the progress of gas through the bed of material onthe moving grate, and material in large lumps cannot be burned with thatdegree of uniformity which is required for best results.

The Lellep process does not contemplate the direct treatment of materialin the form of a sludge or slurry, and it has heretofore been be,

lievedimpossible to achieve satisfactory results with such material. Ithas been proposed, for

example, to dehydrate the slurry on special on the moving conveyor, andnotwithstanding the substantial heat economy of the process, the

application thereof has been limited to the,

necessary to render it usable in the Lellep process. In the preferredform of the invention,

the apparatus of the present invention is associated with apparatus ofthe general character disclosed in the aforesaid Lellep patents, theslurry being dried by a portion of the waste gases flowing into thepredrying and precalcining chambers of the Lellep apparatus.

Itis a further object of the invention to provide, in combination withapparatus for the predrying and precalcining of cement raw material andthe like in the manner described in the aforesaid Lellep patents, adrying chamber in which may be introduced crude sludge from a filterpress, means for directing exhaust kiln gas about and within the dryingchamber to dry the sludge, and apparatus for pulverizing andsubsequently agglomerating the material thus dried for subjection to thepredrying and precalcining steps of the Lellep process.

A further object of the invention is the pro- I vision of a drying.chamber for sludge orslurry in which such material is moved through adrying chamber on a gas permeable conveyor, and in which means areprovided for causing the waste kiln gas to flow downwardly through thetaken in connection with the accompanying drawing, in which Figure l isa side elevation ofapparatus embodying the principles of the invention:1

Figure 2 is a longitudinal vertical sectional view of the apparatusshown in Figure 1; and

Figure 3 is a partial transverse section taken substantially on the line3-8 of Figure 2.

In order to facilitate an understanding of the invention, reference willbe made to the several embodiments thereof illustrated in theaccompanying drawing and specific language employed. It willnevertheless be that various further modiflcationsj'offthe devices,

tion.

' The the material into a kiln for flnal-burning.. "This apparatusconsists essentially ofmeans form; ing a chamber I! in which is disposedpervious support for the material to Preferably the support comprisesa-grateor conveyor l6 arranged to receive the material in the form of athin layer from the-hopper 8, to carry the same in succession throughtwo auxiliary chambers or zones Ill and H, by a partition l1, and todischarge the material from the far end of the chamber I2 into aconventional rotary kiln IS. The hot exhaust gases issuing from the kilnflow over the conveyor l6 and downwardly through the material thereonand through the conveyor, being discharged from the chamber I! by ablower IS. The partion l1, and the baille 18 associated therewith,

serve to direct the hot gases through a circuitous path from the zone Hto the zone II, no

that the temperature of the gases entering thelone Hi is decidedly lowerthan the exhaust temperature at the kiln mouth and the temperaturewithin the zone l-l.

Thus, as described with more particularity in the Lellep patentsL-hereinbefore referred to, it is contemplated that the apparatus besupplied through the hopper 9 with material in the form of relativelysmall lumps or nodules ofgenen'lly uniform size, and these modules arecommonly formed, also :as described in the'patents, by the .-addition ofmoisture to relatively dry material and concurrent agitation in anodulizing or agglomerating The "lower temperature prevailing in zone11.0 is .sufllcientiy high to completely dry these modules, lbllt is notso high the nodules are exploded. or disrupted.

sequently the conveyor 16 carries =W through the zone I I a layer ofseparate and nodules afiording adequate interstices for the.

'passage of gas downwardly through the layer, and adequate and uniformheating at a temperature suflicient to insure partial calcination of the'i'material in the zone 1 l :is

It will be understood that the details. of the structure thus fardescribed constitute per se no part of the present invention, which cong2|. inilwhlch' the'y. -jwill flow avenue illustrated herein, such aswould the province of those skilled in theart-to. are contemplatedas-part of the present inven invention is illustrated as applied werepreparation of cement raw material or: initially in the form of slurryor sludge, for'in' troduction in apparatus for effecting a s calciningoperation prior to theintroduction of- :by the blower may utiiizedfor-"the;

'sists' primarily in the use, in combination with apparatus-suchas'shown in the priorpatents to Lellep," of means for preparing materialwhich is in the form of-a slurry or sludge forfintroduction' into the hop r. s in the desired form of small lumps or nodules. i v, Thus theslurry or sludge is preferably initially drained ortreated in a'fiiterpress to remove ex- .cess liquid, is introduced on a gas pervioussupport consisting of a conveyor 20,1and is carried by the conveyorthrough 'a drying chamber 2| located in the upper portion of the chamberl2 7 above the partition i1 and baflle l8. The chamher 2! may beprovided with a plurality of openls ings 22 with whichis associatedsuitable valve 7 or adjustable closure means communicating with theinterior of the 12, whereby "a controlled 'quantity of the heated gasesflowing ln'theietler" m r be d tt downwardly {throu the-layer orracist,matev rial on the'conveyor.2.,'-.{ 5uitab1elmeansis p vldedto-force the gases 'downwardlyIitliro layer. b la he r e s diiel'm a 8ven'tion thefdesired provision of a gas'exhaust-j'conduitf 4, com

. g i fl w t the cha b 1' b liwl h 'wnsi; v veyor I], anddischargingjwithin the" chamberjj it below the conveyork ll,preferablyadiaeent- 850 the blower" l3, so'Itha't-the reduced pressurejes The dried material from the chamber iltml! discharged between'the'rollsilfor breaking upor pulverizing-the'dried cake-and may'then.be delivered by 'a suitable conveyor fl-to a hopper: 1 v ll andthence'fe'd to an'ag'glomerating indicated generally at 28 in which itis con verted into lumps, pellets, or nodules, as hereinbeforedescribed. This drum may beconstructed as disclosed more particularly inthe patent to Lellep 1,994,718 so as to discharge moish'ire on v thematerial in theform of small drops, and

, while the material is being agitated. Details of the agglomeratingform per se no'part of the instant invention and this drum "may bemodifledas desired. From the drum the nodules are fed into the hopper 8and thereby distributed on the conveyor It forv the partial calciningoperation hereinbefore described.

It willbe noted'from Figure 3 of the drawing that the conveyor ll-whichmay consist of an" endless mesh band, extends, completely across thedrying chamber II and is sealed in' anysuit; able manner as indicated at29 to avoid leakage of gas around the conveyor and to ensure passagethereof through the layer of moist materials ,lt appreciated; however,thatr'ar'lcertain amount-off heat "fmfidrvins is madefavailable'through'the walls'defining thechamber 2|,

the hot g'asestraversethe length of the chamber in passing from zone I!to zone I. of the :principal chamber i2; Regulation'of gas pressure andtemperature may be effected by means!!! thevent valves ll 12 inthestacks ll respectively as well as by adjustment lengthwise inthechamber i2 ofthe partition ll.

Having'thus described the invention, what-is. claimed as new and desiredto be securedby'Let ters PateIit is: I t 1. In apparatus for preparingcement raw material and the like in the form of slurry or sludge forintroduction into a kiln, the combination with means for filtering thematerial to remove excess liquid therefrom, of a gas permeable conveyorfor receiving the filtered material in a relatively thin layer, meansfor forcing hot waste kiln gases downwardly through the material and theconveyor to dry the material, means for crushing the dried material,means for s'upplying moisture to the crushed material and simultaneouslyagitating the same to form the material into lumps or nodules ofrelatively small size, and means for delivering the nodules to a secondgas permeable conveyor for a partial calcining operation prior tointroduction thereof into the kiln.

' 2. In apparatus for preparing cement raw material and the like in theform of slurry or sludge for introduction into a kiln, the combinationwith a gas permeable conveyor for receiving the material in a relativelythin layer, means for forcing hot waste kiln gases downwardly throughthe material and the conveyor to dry thematerial, means for forming thematerial into lumps or nodules of relatively small size, and means fordelivering the nodules to a a layer of the material, means for causinghot waste kiln gases to flow within said chamber and 4. In apparatus forpreparing cement raw material and the like in the form ofslurry orsludge for introduction into a kiln, the combinasecond gas permeableconveyor for a partial cal 1 cining operation prior to introductionthereof into the kiln.

- 3. In apparatus for preparing cement raw 7 material and the like inthe form of slurry or sludge for introduction into a kiln, the combination with a drying chamber, of a gas permeable support arranged withinsaid chamber to receive tion with a drying chamber, of a gas permeablesupport arranged within said chamber to receive a layer of the material,means for causing hot waste kiln gases to flow within said chamber anddownwardly through the material therein to dry the same, means forforming the dried material into lumps or nodules of relatively smallsize, a second gas permeable support for receivv ing the lumps ornodules of material, means causing hot waste kiln gases to flow downthrough the material on said second support to partially calcine thematerial before delivery thereof to the kiln, and means for dischargingthe gases from said chamber beneath said second support.

CARLO WANNER.

